This invention relates to battery caps and particularly to those which permit the condition of the electrolyte within the given cell to be determined without removal of the cap.
Battery caps which permit viewing of some type of indicator in the battery cap have been well-known. Several of the designs which have been used are illustrated by the Sinclair patent, for example, U.S. Pat. No. 3,170,325, which has a cylindrical cap with a window.
Another type of construction is shown by the Gosheff U.S. Pat. No. 2,484,163 which discloses a transparent window for viewing the upper tip of a float.
Another battery cap with an indicator is disclosed in the Sakamoto U.S. Pat. No. 3,895,964. This design has a floating ball which indicates the level or specific gravity of the electrolyte in the storage battery.
A very common type of battery cap construction which has been used extensively is shown by the Melone U.S. Pat. No. 3,893,339.
The above patents all show devices of the general type in which a battery indicator cap has a float with some type of indicator. However, the battery cap designs mentioned above have one or more disadvantages which the subject invention overcomes.